EXTRAVASATION DETECTION APPARATUS AND METHODS
Described herein is an extravasation tester that pinches an infusion line closed between a wheel and a platen, and then peristaltically withdraws fluid into the infusion line as the wheel is rolled away from a puncture site. Extravasation is determined to have occurred if little or no blood appears in a sight chamber positioned near the puncture site when a test fluid is withdrawn into the infusion line from the puncture site.
The present disclosure relates to extravasation detection. An extravasation tester withdraws fluid back into an intravenous infusion line in conjunction with performing an extravasation test. The extravasation test is “passed” if a richly dark density of blood appears in a sight chamber positioned near a puncture site when a test fluid is withdrawn into the sight chamber from the puncture site. The extravasation test is “failed” if little or no blood appears in the sight chamber when the test fluid is withdrawn into the sight chamber from the puncture site.
BACKGROUND OF THE INVENTIONPatients can be severely injured when fluids that are intended for intravenous delivery are delivered outside a targeted vein. Possible consequences of prolonged delivery of an infused fluid outside the targeted vein include irritation, tissue necrosis, compartment syndrome, disfigurement, loss of limb function, amputation, and even death of the patient. Extravasation occurs when the outlet of a cannula is misplaced or becomes dislodged to a region outside the vein. Extravasation refers herein to improper placement or movement of the outlet of an intravenous cannula to a region outside the targeted vein, or delivery of a fluid that is intended for intravenous delivery outside the targeted vein.
Various methods are known to the art for detecting extravasation in an infusion system. Such tests can be employed for minimizing delivery, outside a targeted vein, of fluids intended for delivery within the targeted vein. If extravasation is detected, then the flow of delivered fluid can be stopped when the faulty condition becomes known.
In one method of detecting the proper placement of a cannula during an infusion, the DC component of the pressure is monitored in an infusion line. Proper placement of the cannula in a vein is detected when the pressure in the infusion line tracks the DC component of the pressure in the vein. Extravasation is determined to have occurred if the monitored pressure occurs outside a prescribed pressure range. However, this method suffers from the possibility of failure to detect extravasation, because an apparently proper pressure can be produced while the cannula is outside the vein, resulting in significant accumulation of extravasated fluid and possible injury when the infusion is continued under the undetected faulty condition. Furthermore, the DC pressure method requires sophisticated electronics, which may be unavailable in some emergency situations such as accident sites and battlefields, unavailable at severely budget-constrained clinics, or which may be unsuitable for flowing vesicant or cytotoxic medicines, for very low flow applications, or for any other applications in which it is preferred not to use a powerhead for infusing a fluid. A powerhead is a powered pump that positively actuates forced delivery in an infusion line.
Another extravasation detection method uses the AC component of the vein pressure. Both veins and arteries have a pulsing AC pressure component. The AC pressure component can be detected as either a variation in pressure or a variation in flow in an infusion line, according to U.S. Patent Application Publication No. 2007/0112329. The pulsing AC pressure is detected in the infusion line if the cannula is properly placed in the vein, and not detected if extravasation has occurred. If a pulse is not detected for a few seconds at any time after the start of an infusion, then extravasation is determined to have occurred. However, like the DC pressure method, the AC pressure method requires sophisticated electronics which may be unavailable or unsuitable for the same above listed reasons.
Numerous references disclose extravasation detection with infrared, RF, microwaves, ultrasound, light, pressure response to a test injection, or changes in temperature. These methods require sophisticated electronics and many of them involve probes which are applied separately from the infusion line. Extravasation is inferred from a measured change that is a secondary consequence of accumulation of extravasated fluid. Assumptions are made and relied upon as to how tissue properties will change when a delivered fluid accumulates outside a vein, and significant quantities of extravasated fluid may accumulate as the infusion is continued under an undetected faulty condition if these assumptions fail.
U.S. Patent Application Publication No. 2013/0310743 discloses a test that detects extravasation by monitoring for entry of blood near the cannula when the flow of delivered fluid is momentarily reversed by a finger-type powerhead. However, in some applications, it is preferred not to use a powerhead, such as for intravenous delivery of vesicant or cytotoxic medicines, for medicines that are delivered at a very low flow rate, or for any other medicine or circumstance in which forced delivery of the medicine is contraindicated.
In one commonly used extravasation test, an infusion line is backflowed with a syringe. A syringe is connected in flow communication with the infusion line between a puncture site and a point in the infusion line at which the flow has been restricted or shut off. Proper placement of the cannula is detected if blood flows back into the infusion line from the puncture site when the syringe's plunger is pulled back. This method requires the syringe or other extra equipment not already present on the infusion line, which must be supplied for performing the test. Repeated testing with this method consumes many syringes, the total of which may be expensive, and the test itself requires significant effort to perform, all of which present a deterrent of using this method to check or monitor proper placement of the cannula. Furthermore, concerns are raised about sterility when a syringe or other additional equipment is placed in flow communication with an infusion line.
“Roller clamps” have been used for throttling the flow in an infusion line. The roller clamps shown in U.S. Pat. Nos. 6,422,529 and 8,313,081 have a wheel that pinches an infusion line against a bottom wall having a relief groove in order to throttle an adjustable, nonzero flow throughout the substantial length of the wheel's range of travel. The roller clamps shown in U.S. Pat. Nos. 6,422,529 and 8,313,081 do not aim to pinch the infusion line fully closed and then peristaltically withdraw fluid back into the infusion line by movement of the point of closure.
Based on the forgoing, there is a need for an extravasation tester that pinches an infusion line closed between a wheel and a platen, and then peristaltically withdraws fluid into the infusion line as the wheel is rolled away from a puncture site. Extravasation is determined to have occurred if little or no blood appears in a sight chamber near the puncture site when fluid is withdrawn into the infusion line from the puncture site.
SUMMARY OF THE INVENTIONDescribed herein is an extravasation tester used for performing an extravasation test. The extravasation tester pinches an intravenous infusion line's delivery tube closed between a wheel and a platen. The wheel pinches the delivery tube fully closed against the platen when the wheel is moved out of a free-flow region and into a tube-pinching region above the platen. Fluid is peristaltically withdrawn into the infusion line from a puncture site by movement of the point of tube closure between the wheel and the platen as the wheel is rolled on the delivery tube away from the puncture site. If a richly dark density of blood appears in a sight chamber positioned near the puncture site when the wheel is rolled away from the puncture site, then the extravasation test is said to be “passed”, and the wheel may be returned to the free-flow region in order to resume the infusion. If little or no blood appears in the sight chamber when the wheel is rolled away from the puncture site, then the extravasation test is said to be “failed”, and the delivery tube is left in a closed state until a corrective action is performed.
The extravasation tester 100 uses an architecture that is very similar to the conventional architecture of the “roller clamps” that are used for throttling a nonzero flow. The extravasation tester 100 may be dyed, painted, or decaled with a unique color or pattern to distinguish it from otherwise similar-appearing devices having different functions, which may also be mounted elsewhere on the delivery tube 116. For example, a yellow and black striped “safety” pattern may be used, denoting the extravasation tester's 100 safety-related function.
The extravasation tester 100 has mirror symmetry about a vertical plane passing through the dashed lines adjacent each of the arrows in arrow pair 12 in
Although it is foreseen that a flow-throttling region may also be incorporated into the extravasation tester 100 within the free-flow region 113 or between the free-flow region 113 and the tube-pinching region 111 shown in
The frame 109 also has a pair of opposing guide slots 110, of which one of the slots 110b is visible in
The source of infused fluid 102 is shown as a hanging bag or bottle, but may comprise a plurality of hanging bags or bottles, possibly in combination with flow controllers, pumps, check valves, drip chambers, tube mergers, connectors, ports, or other conventional infusion accessories, which are provided separately from the extravasation tester 100. The sight chamber 118 is a transparent tube or window through which fluid near the puncture site 120 may be visually or optically inspected. The sight chamber 118 may be a transparent portion of the cannula 122 or a transparent portion of the delivery tube 116 adjacent the puncture site 120. Components are not drawn to scale. For example, the sight chamber 118 is enlarged herein for ease of illustrating test results, and the source of infused fluid 102 is minimized to leave more room for showing the inventive elements. Fluid is allowed to flow freely in the delivery tube 116, and the sight chamber 118 contains fluid originating from the source of infused fluid 102, when the wheel 104 is centered over position 21, as shown in
At the end of the first step shown in
Fine control is afforded by the extravasation tester 100, and this fine control enables performance of a “passed” extravasation test with minimal incursion of blood into the cannula 122 and sight chamber 118. By choice of inner diameters of the delivery tube 116 and sight chamber 118, a ratio, of blood incursion distance in the sight chamber 118 to wheel 104 travel distance, can be made less than 1 or greater than 1, as desired. For example, if the inner diameter of the sight chamber 118 is made to be one half the inner diameter of the delivery tube 116, then the blood incursion in the sight chamber 118 moves an additional 4 millimeters per additional millimeter of movement of the wheel 104.
The extravasation tester 100 can be mounted on the delivery tube 116 in a direction opposite the mounting direction shown in
The mounting direction of the extravasation tester 100 shown in
Claims
1. An extravasation tester, comprising:
- a frame having a hollow bore for receiving an intravenous infusion delivery tube;
- a platen on an inner surface of the hollow bore;
- a manually rotatable wheel having a circumferential outer surface and opposing axial posts; and
- opposing slots in the frame for receiving the opposing axial posts of the wheel so that the wheel is rotatable about its axis and translatable along the slots in the frame;
- wherein the slots and the surfaces of the hollow bore are configured so that: (a) when the wheel is in a free-flow region of the frame, the outer surface of the wheel does not pinch the delivery tube closed against the platen, (b) when the wheel is in a tube-pinching region of the frame, the outer surface of the wheel pinches the delivery tube closed against the platen, and (c) when the wheel is rolled on the delivery tube in the tube-pinching region of the frame, the point of tube closure moves along the delivery tube with the wheel.
2. A method of performing an extravasation test, comprising the steps of:
- providing the extravasation tester of claim 1;
- rolling or sliding the wheel out of the free-flow region and into the tube-pinching region, thereby closing the delivery tube between the wheel and the platen;
- rolling the wheel on the delivery tube away from a puncture site, thereby withdrawing a test fluid from the puncture site and into a sight chamber; and
- performing the following, subject to the respective conditionals in each: (a) if a substantial concentration of blood is present in the sight chamber within or upon completion of the withdrawal of the test fluid into the sight chamber, returning the wheel to the free-flow region, and (b) if little or no blood is present in the sight chamber upon completion of the withdrawal of the test fluid into the sight chamber, leaving the delivery tube in a closed state until a corrective action is performed.
3. An intravenous infusion system, comprising:
- the extravasation tester of claim 1, mounted on the delivery tube;
- a source of an infused fluid;
- a cannula, intended for insertion into a vein at a puncture site; and
- the delivery tube, adapted for carrying the infused fluid from the source and toward the cannula.
4. The infusion system of claim 3, further including a sight chamber for viewing or detecting a test fluid withdrawn from the puncture site.
Type: Application
Filed: Sep 19, 2014
Publication Date: Mar 24, 2016
Patent Grant number: 9572933
Inventors: Shawn Grannell (Ann Arbor, MI), Donald E. Gillespie (Ann Arbor, MI)
Application Number: 14/491,316